Galvanometer movement mounting



July 219, 1947g v C, M, HATHAWAY 2,424,823

GALVANOMETER MOVEMENT MOUNTING Filed sept. 25, 1944 j?? i Patente-d July 29, 1947 GALVANOMETER MOVEMENT MOUNTING Claude M. Hathaway, Denver, Colo., assignor to Hathaway Instrument Company, a corporation of Colorado Application September 25, 1944, Serial No. 555,685

Claims. 1

The present invention relates to galvanometers and more particularly to a watt galvanometer.y

For certain applications it is desirable to obtain a record of electrical quantities as measured in watts, and for this purpose it is necessary to use a watt galvanometer. Frequently it is desired to obtain a plurality of records of different values at the same time and to accomplish this it is necessary to provide an oscillograph with a plurality of watt galvanometers which preferably should be relatively compact so that a plurality of traces may be obtained. In order to obtain comp-actness and yet avoid an expensive structure, it is necessary to provide an improved type of galvanometer cell. In accordance with the present invention an improved type galvanometer cell is constructed so that the sides are formed of `two blocks of metal which by machining operations are recessed so that when the two blocks are joined together at least four surfaces of the cell block are completed.

It, therefore, is an object of the present invention to provide an improved cell block for a watt galvanometer which is simple and economical to manufacture.

It is another object of the present invention to provide an improved watt galvanometer which is relatively easy to assemble during manufacture.

Other and further objects of the present invention subsequently will become apparent by reference to the following description taken in connection with the accompanying drawing wherein v Figure 1 is a front View of a watt galvanometer constructed in accordance with the present invention;

Figure 2 is a side view of the watt galvanometer shown in Figure l;

Figure 3 is a side view in cross section of the front plate of the cell block; and

Figure 4 is a front View of the principal body portion of the cell block.

Referring .to Figures 1 and 2 there is shown a watt galvanometer having a base II provided with a, pin I2 which extends through a depending portion of la. subbase I3 so that the subbase at its other end may be raised and lowered in order to determine the elevation of the trace to be recorded by the light reecting mirror on the galvanometer element. On the rear portion of the subbase I3 there is positioned a screw assembly I4 of conventional structure which operates to raise and lower the rear end o-f the subbase I3. The subbase I3 is biased downwardly by a tension spring arrangement contained within a vertical housing I5. Another vadjusting rod I6 extends through the subbase I3 where it is connected to a lever I7 having an upwardly extending member I8 arranged to engage a slot in a mounting plate I9. The mounting plate I9 is secured to the body of the cell block of the galvanometer by a screw or screws 2|. The body of the cell block is arranged for pivotal movement together with the mountingV plate I9 by a pivot screw member 22. The structure thus far described is of a conventional type which is well known in the art and does not constitute a part of the present invention. Hence these elements are not shown or described in detail. Y

The galvanometer cell constructed in accordance with the present invention includes a body portion 23, a block back cover plate 24 and a front cover plate 25. The back cover plate is provided with a gasket 26 and is secured in position by a plurality of screw members 21 so as to completely enclose the back of the Lcell block. The front plate 25 is also provided with a gasket 28 and the plate is retained in position by a plurality of screws 29. Mounted on the front plate 25 is a lens holder 3l provided with a suitable gasket 32 and retained in position by a plurality of screws 33. The lens holder 3l has a cylindrical portion 34 which passes through a circular aperture in the yfront plate 25 and extends into a circular recess in the cell body 23.

The front plate 25 is shown in greater detail in Figure 3 from which it will be seen that there is provided a binding post 35 so that a connection may be made to one extremity of a bilar galvanometer element 36 having its other end connected to ground through a stud member 31. The galvanometer element 36 is provided with a reiiecting mirror 38 and proper tension of the element is provided by a lpulley 39 mounted on a bell crank 4I the position of which is determined by an adjusting mechanism contained within a housing 42. The housing contains a tension spring 43 having one end connected to the bell crank 4I and the other end connected to a threaded adjusting screw member 44. The housing 42 also serves as a filler cap for filling the interior of the cell with oil. A cap 45 is provided to close the opening 42 and to permit convenient access through the adjusting screw 44 to adjust the tension to be applied to the bifilar gal- -vanometer element 36 by the tension spring 43.

The cap 45 may lbe of the type having an oil resistant resilient diaphragm 46 to allow for expansion and contraction of the oil within the cell block. The front plate 25 is provided with point along the longitudinal opening 52 .the metal,

blocks 49 and 5| are provided with recesses 54 and 55 which are complementary to and are: adapted to receive the cylindrical portion '34'of` the lens holder 3|. Each of the blocks 49 and 5| is also recessed from the rear to a Apoint closelyv adjacent the front surface. The block 49 Vtherefore has a recessed portion 56 and the blocklil has a recessed portion 5l so as to provide adequate space-for mountingA within' the block- 23 a magnetic :core and'coil. The two block portions 49 .-a-nd 5| are joined together by friction pins 58 lextending between the sides *of the cell block |body 23. The transversely extendingpins 58 also serveias mounting means for supporting the magnetic Vcore 59 which is provided with a coil or winding 6| The magnetic coil 6| is connected to suitable terminals-62 and `63 vmounted at the top of the body-23. By forming the body 23 of two similarblocks of metal with recesses cut therethroughY as illustrated in Figure 4, it will be appreciated thatvmanufacturing operations are greatly facilitated-aand' hence the cost thereof is reduced. The arcuate recesses 54 yand 55 at the front of the body23 cooperate with the cylindrical lens portion 34 toassist in accurate positioning of thegalvanometer element 36 between the pole` piecesrof the magnetic core 59.

While for the purpose of .describing and illustrating, the present invention a preferred embodiment has Abeen .shown in the drawing, it is to be understood that Ysuch variations are contemplated .as may be commensurate with the spirit and scope .of the invention as defined in the appended claims...

Thisinvention is hereby claimedas follows:

1. A ,cell for a watt galvanometer comprising a bodyA formed of two similar recessed blocks of metal, a front cover anda back cover for said body` said recessed blocks of metal beingassembledwith the recesses in opposition to each other so that the body has arecess extending from the back of the body to a plane adjacent thefront of the body, said recess beinginter-connected with the front of the body by a'narrow elongated opening having adjacent the central portion thereof arcuate recesses for vreceiving a cylindrical member to be mounted on said front cover.

2. Acell for a galvanometer comprising a body formed of two similar blocks of metal each recessed from one surface to a plane adjacent the opposite surface and recessed by a smaller recess interconnectingsaid plane with the opposite surface, said blocks having a plurality of apertures transversely arranged relative to said iirst recesses, and a plurality of friction iit pins mounted in said apertures 'to assemble said blocks into a cell whereby said latter recesses form a narrow elongated opening .communicating with a chamber formed by said rst mentioned recesses.

3. A watt galvanometer comprising a body formed of two similar blocks of metal, and front and back covers therefor, each block of metal having a recess extending from the back of said body `to a plane adjacent the front of said body, saidrecess being interconnected with the front of said body by a narrow elongated opening, said elongated opening having adjacent the central portion thereof arcuate recesses for receiving a cylindrical member mounted on the front cover, a plurality of friction iit pins mounted in transverse apertures in said blocks of metal to retain said blocks together to form said body, a magnetic core structure mounted within said body between said transverse pins, a coil for said core, electrical connections mounted on top of said body for connection to said coil and a vibratory galvanometer element .supported on the back side of said .front cover.`

4. Av watt galvanometer comprising a body formed Vof two similar .recessed blocks of metal, a plurality of friction iit pins mounted in transverse apertures -in said blocks of metal to retain said blocks together to-form said body, said blocks of metal when assembled being provided with a recess extending from the back to a plane adjacent the front of said body, a narrow elongated opening interconnecting the front of said body with said recesses, front and back covers for said body, arcuate recesses formed in said blocks of metal adjacent thedcentral portion of said elongated` opening, a lens holder mounted on the front cover having a rearwardly extending cylindrical portion adapted to iii; in said arcuate recesses, a vibratory galvanometer element supported by said front cover, a magnetic-core structure mounted .within'said body and supported by said pins, and a-coil for said magnetic core.

5. A cell for a galvanometer comprising a body formed 1of two similar blocksof metal7 and front and back covers for said body, each block of metal being recessed :from one surface to a pla-ne adjacent the opposite surface, and asmaller recess Yinterconnecting said opposite surface with said .rstrecess .atsaid plane, said blocks Abeing assembled with recesses arranged in opposition to each other to form at said opposite surface a narrow elongated, opening communicating with aflargervopening formed by said first mentionedrecesses, saidfront cover being mounted across said narrow elongated opening, and saidback cover vbeing mounted to yclose the larger chamber formed. by rsaid first mentioned recesses.

CLAUDE M. HATHAWAY.

REFERENCES CITED The-.following references lare of record in the le of this patent:

UNITED STATES PATENTS- Number Y Name Date 1,193,979 Blondel Aug, 8, 1916 1,370,179 y Angus Mar. 1, 1921 1,951,578 Peters Mar, 20, 1934 v2,161,744 McCarty June 6, 1939 2,368,831 Hathaway Feb, 6, 1945 

